(e.g., a dipole or driven element) to an
unbalanced line such as coax which
is not balanced, thus the name, Balun. The 1:1
choke "balun" is not actually a balun. It's function is to
help eliminate rf currents from flowing on the outside of coaxial
cable using the principle of choke action. Another "name" for it is
the air choke.

In transmitting antennas, this is accomplished
by presenting a high impedance (resistance), to RF currents flowing
outside the coax shield. This forces currents in each side of a
driven elements to be equal. This is especially important in beam
antennas because it prevents distortion of the beam's pattern caused
by unequal currents in the driver(s). In a simple dipole, the balun
(choke), assuresthat the dipole, and not the feed line, is doing
the radiating!

When you connect center fed antennas, like
dipoles, V's, triangles, yagis, rhombics, loops and so on, to
coaxial cable, unless care is taken, it is not difficult to end up
with feeder radiation. Not only can the
loss in power be quite significant, but the radiation
characteristics of the antenna system will also be seriously
compromised.In laymen's terms, it won't be what you are
expecting from the pattern of your antenna. As the feedline
becomes part of the antenna, currents can flow from the line into
the mains and on TV cables, metal masts and yagi booms, causing a
variety of EMI problems that can be very difficult to trace.
Frequently these problems are simply due to unbalance - and the
solution is the humble air choke.If an antenna system is fed at
center with a parallel conductor line (provided that correct
installation procedures are followed) balance will be maintained,
USING A BALUN, with currents in equal and opposite phase canceling
each other out.

When the connection is
to a coaxial cable, WITHOUT A BALUN, this cannot occur because
currents flowing inside the cable from the connection to the inner
conductor are separated from those flowing on the outside from the
connection to the shield, and the result is unbalance causing feeder
radiation. However, if the two electrical circuit elements (antenna
and coaxial cable) are coupled using a balan, balance will be
maintained.Enter.....The Ugly
Balun!.....

"No costly ferrite-cores are
needed, just a short length of 3 to 5 inch size plastic pipe, about
25 feet of 50ohm coax plus some nylon cable
ties.

Solid-dielectric coax is best for this application
because foam-dielectric has a tendency to allow a change in the
conductor to conductor spacing over a period of time if it is bent
into a tight circle. This can eventually result in voltage breakdown
of the internal insulation.

The required length of the
plastic pipe depends on the diameter and length of the coax used and
the diameter of the pipe. For RG-213/U coax, about one foot of 5
inch size pipe is needed for a 1.8MHz to 30MHz balun. For 3.5MHz to
30MHz coverage, about 18 to 21 feet of coax is needed. This length
of coax is also adequate for most applications on
1.8MHz.

18 to 21 feet should
cover all of 160 through 10 meters.The
number of turns is not critical because the inductance depends more
on the length of the wire (coax) than on the number of turns, which
will vary depending on the diameter of the plastic pipe that is
used.

The coax is single-layer close-wound
on the plastic pipe.

The first and last
turns of the coax are secured to the plastic pipe with nylon cable
ties passed through small holes drilled in the plastic
pipe.

The coil
winding must not be placed against a
conductor.The name of this simple but effective device is a choke
balun.NOTE:
Some people build choke-baluns, without a plastic
coil-form, by scramble-winding the coax into a coil and taping it
together. The problem with scramble-winding is that the first and
last turns of the coax may touch each other. This creates two
complications. The distributed-capacitance of the balun is increased
and the RF-lossy vinyl jacket of the coax is subjected to a high
RF-voltage. The single-layer winding on the plastic coil-form
construction method solves these problems since it divides the
RF-voltage and capacitance evenly across each turn of the
balun"....AG6K

Credit for this article goes to AG6K,
Rick Measures and was edited from a Pre-copy version of another
article titled "A BALANCED - BALANCED ANTENNA TUNER" published in
QST,February, 1990.

Video from K8CPA and his ugly balun
-----------------------------------------------------------------Step
by Step Sequence of building the "Ugly Balun" incorporated as a
center insulator also using PVC by KC7AVA. (Sequence
is from left to right and down page.)

Here is my version of an "Ugly
Balun"Made from PVC pipe with end caps and
cable glands. Coax is RG8-X from DX-Engineering. Easily transferred
between antennas because of the PL-259 connectors on each
end.Ron - WB2RCB

Lots more "Ugly Balun" photos, ideas and
installations sent in by users
below!

Here are examples in the pictures
below using cable ties on PVC pipe forms which work well also. Your
choice! (Imagine the coil form is removed). Pictures are showing
how to secure the coils together. Do not let the first and last
coils touch!

Picture above
courtesy of VE7AVV

Picture above courtesy of KC2NXV (now N4NYY) shows using
2 pvc couplers joined and glued using about 2 inches of 4 inch PVC
pipe, so the couplers would adhere and be
stronger.

More "Ugly
Balun" ideas from DAVE THOMAS, M3RUH
BELOW:

The Dave
Thomas, MW3RUH BOTTLE SPECIAL!

Dave uses a plastic drink bottle as a form. He
installs an S0-239 in the bottle cap and antenna connectors
on the other end!NICE TIP DAVE!

Paul, G4APL,
has brought together some excellent examples on how to construct and
build Choke Balun in the pictures above and the information below to
share with us:

Paul decided to
build two or three of them, depending on what material could be
found in the shed.

The idea was to
add a balun to the HF beam, a Mosley Mustang Mark3 3 element 10,15,
20 metre trapped yagi. This is fed with co-ax and has the Mosley
earth strapped at the feed point. The beam has been adjusted for the
low end of the HF (High Frequency) bands.

Paul had used a
commercial balun in the 1970?s before and burnt this one out. It was
supposed to be rated to 1 kilowatt pep. (peak envelope
power).

Using the
information material from the instructions for the "Ugly Balun"
above, it was time to see what was in the
shed.

A short
length of 4 inch drain pipe was located that was left over from the
90 foot of drain pipe laid underground that carries the RF cables.
Also found a 2 inch piece of down pipe.

Materials:
HF Beam
Balun

12 inches
length of 4inch diameter PVC drain pile

cable
ties

18 foot of
RG58

two suitable
cable plugs

Having got all
the required tools out, it took Paul and hour to build the Ugly
Choke Balun as pictured above.

The HF Balun is
attached vertically to the Stub Mast at the Mosley Mustang Mark3
beam.

Paul was very
surprised with the results. Testing the aerial and Balun with 250
Watts the standing wave was surprisingly good.

Never seen this
beam produce these results before!

14.005MHz to
14.150MHz 1.1:1

14.200MHz
1.2:1

14.250MHz
1.4:1

14.300MHz
1.9:1

21.005MHz to
21.300 1.1:1

21.400MHz
1.2:1

28.005MHz ?
28:400MHz 1.1:1

28.500MHz
1.2:1

Now to do some dxing and
see how the aerial performs.Hope the above is of use to
you.........73 Paul
G4APL

============================================

More
from ZL1ALZ, JOHN from New Zealand!"Ugly Balun" construction
used on a 40 meter vertical!

Closeup of the
ZL1ALZ "Ugly Balun"

The VE2ITZ
Balun with Sloper Antenna!

Exellent results! Never had such an easy time at
tuning the sloper antennas with the "Ugly
Balun"!By the way; the balun consists of 20 feet of coax
wound around a 2 and a half inch diameter plastic bottle. I then
proceeded to put gaffer tape to hold it in place.Et Voila!
Cheers and 73 de VE2ITZ in Montreal,
Canada

==============================================="Ugly Balun" installed on the A3S 3 Element Beam
at the KO4MAX QTH!This update was compiled
from various emails:"Hey, we don't think it's
so ugly!"

KO4MAX
deserves the credit just for putting up with
me.

I wanted to
add (in this update), that 21 feet is the length of coax used
in the construction.

We put the
antenna up on a Sunday afternoon, and it was sketchy to say the
least.

The auto
tuner in his Icom 746 Pro kept engaging automatically (even
when it was turned off).

I knew it had
to be coupling with the feed line.

So, I showed
him your Ugly Balun page and then the Hy Gain manual I have, which
calls for 12 turns 6 inches in diameter.

He read the
Cushcraft A3S/40m manual which states 8 turns at 6 inches in
diameter.

After much
debate we went with your design. See photos
below.

Monday, enter
the Ugly Balun.

Now, the
antenna works and it works well.

The second
day on the air (Tuesday) he sent an email informing me that "it
rocks" which is a quote.

He also says
it's a big improvement over the dipoles he had on those
bands.

75/80 meters
and the warc bands is all that is left in his
shack.

We'll rework
those dipoles for those bands.

Thank you for
your contribution and website!

We found the
Ugly Balun to be a huge help when it came time to stop the feed line
coupling.

We think
it gives this big A3S/40m (10-15-20-40m 3 Element
beam) "character".We installed this at KO4MAX in South
Florida. See photos below:

We
used 4.5 inch bolts through the half pipe (split in two
vertically).We inserted 4 inch stand-offs and bolted the 4.5
inch PVC to the half pipe.We used tie wraps for a temporary
installation (During testing). Stainless steel clamps were used
in final installation.We plan to install U-bolts to permanently
mount the assembly to the mast pipe.

No more coupling
with the coax after installation.Tested with the MFJ-269 Pro
Antenna AnalyzerNearly perfect on all 4
bands!

This thing, over 2 years later, still working like a
champ.This installation should provide many years of
service

Came down off the tower and made our first
contact with Italy IZ5ILF - Max

The work, including the Balun winding was done
by my friend Matt, AC8AC.The Antenna is a homebrew G5RV, that
actually works! 73 es gud dx DE K8CPA

VU2UWZ Version

YV5GRB Version "I want
to thank you for the usefull information and differentexamples
on your web page, I could understand and build two 1:1 chokesfor
my 5BTV phased verticals, I also helped other local hams
withthis project. They work!."73 de Eduard
(YV5GRB)

Below are some ideas from Kelvin, G4ZTD

Balun shown attached to vertical antenna

Antenna connector end shown

Balun shown mounted to gray pipe

SO-239 end

I used 21 feet of rg58 on 4 inch drain
pipe, I used clear 3mm plastic sheet cut to fit in the ends,
glued these in using hotmelt, then at one end I fitted an so239
connector and the other end has terminal posts to connect to the
antenna and ground. You will notice the vertical slots cut into
the brown tube. These are to allow any water to run out of it.
The gray pipe was glued to it so I could attach it to the pole
with cable ties.

Funny thing is it looks quite cool.I
have tested it on 20 mtrs 14.230 (SSTV) and the swr meter hardly
moves.

After reading
the article on the Pro's and Con's of the "Ugly Balun", I decided to
make one and install it on my home brew 3 Element 17 Meter
Yagi.... after all one home brew deserves another
right?

Looks like it
is going to work out just fine. I used 21 feet of 9913 Flex
around a 3 inch schedule 40 PVC pipe.

The dipole
has a split driven element so feeding it was just like feeding a
wire dipole. Tuned up ok but may have to adjust the DE for a
little better standing wave ratio, but all in all its a thing
of beauty.

Ugly is just
a state of mind!

Catch ya on
the air,

Danny

N5DRG

This just in from
K2NCC! Frank and his ham friends calls it his "bee-hive"
balun!

I made my first
home-brew 20M dipole late 2010, and quickly found myself faced with
a challenge. Too much RFI into the shack. On a local
technical net, I mentioned my woes and attempts to eliminate cooking
myself without relocating. More than one ham recommended the
"UGLY BALUN". My first thoughts showed my ignorance as I
didn't take it as a serious solution. But glancing around the
shack I saw I had enough to try it anyway, and the opportunity to
make another antenna was appealing.

Boy, am I glad I
did! A quick GOOGLE search led me to the Hamuniverse.com
site and this Ugly Balun article. Adding the
air-wound common-mode choke (Ugly Balun sounds so much better!) It
reduced my field-strength meter swing from 10+ to barely 1 anywhere
in the room. Now, I too recommend it to anyone using a
dipole. Ugly doesn't mean stupid! In ham radio lingo, it means
beautiful!See photos below.

How I built the "bee hive"
ugly balun:I used a large pump-type shampoo bottle,
about 5" tall, 4" diameter, upside down. After
measuring and tapping holes for my tie-wraps, I wound about 20' of
RG8x around the plastic bottle, and used a PL-259 connector on one
end to bridge with the feed-line. The other end of the coax
was center conductor to one side, shielding to the other, making the
dipole connection points. I used nuts-n-bolts and a couple of large
washers on both sides of the bolts for stress-relief on the plastic
and to secure the antenna legs. This assembly allows me to
remove the balun from the system easily and add/remove bands with
little effort. A threaded brass loop from an old table-lamp
lets me use a simple double-ended snap hook to a eye-bolt screwed to
the eve of the house. I finished off the project by applying a
generous amount of liquid tape to anywhere that water could seep
in.

Now I'm happy as a (uncooked!) clam. (I should'a said
ham!!). What a superb and simple solution. Thank
you!Frank, K2NCCHillsboro,
Oregon

From 2E0RCR

This is made
from 21 feet of RG213 Coax and a little bit extra to help connect
the balun to the antenna.

I have
decided to mount the choke on a wooden fence panel as illustrated in
left picture below. It was too fiddly getting up to the CP6
coaxial mounting so I just patched into the
coax.

Balun mounted on fence below
antenna.

Results:

I could
never tune 80m but now I can. There is
considerably less noise than before.

I am so
impressed I have made another one to take portable with me for
when we attach large verticals to portable masts. Hopefully this
will help some of the RF feedback issues I have been
having.

Kind
Regards

Robert
2E0RCR

Here is my new "choke balun" in
the 2 images above for the Diamond CP-6.

I can now tune better. 80m came
alive.

Less background noise all over
the bands.

I feel happy to try the Ugly
Balun.

73, Bert EA8AGF

This one from
HA5OGLI've built your "Ugly balun".Mine really
looks ugly. :-) But it works good! 18 turns on 110mm PVC
pipe. It was built from left overs from my syster's house
renovation.Thanks, and 73s! I hope to see you on air!Op.:
Levente

"Don. I built one
of the "Ugly Baluns". I was using it on a dipole for 80/40
meters. I had some TVI without the balun, so no doubt the
feedline was radiating. With the balun attached, the TVI
completely disappeared. I built a second one as I had the same TVI
problem with an R7. The balun cured this as well. I can run my
linear now with no problems as all. So I appreciate your
expertise and your article." Thank you. Best Wishes
Russ, VE6VKCHECK OUT RUSS'S ANTENNA PROJECTS ON THIS SITE:20 METER MINI BEAM

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